Figure 1. Stem density distributions by cycle in Gettysburg National Military Park (GETT). Cycle 1: 2007 – 2010; Cycle 2: 2011 – 2014; Cycle 3: 2015 – 2018; Cycle 4: 2019 – 2023. Figure A shows regeneration densities by size class. Figure B shows tree density by diameter at breast height (DBH) increments. Error bars are 95% bootstrapped confidence intervals to account for non-normal error. An asterisk denotes a linear DBH distribution that is indicative of long-term recruitment failure.
Figure 2. Regeneration Debt status for the most recent 4-year census (2019 – 2023) in Gettysburg National Military Park (GETT). Flat Tree Diam. Dist. stands for Flat Tree Diameter Distribution. If TRUE, the density of small trees is lower than expected due to chronic regeneration failure. Sapling/Seedling Composition is the % of total stems composed of native canopy-forming species. Sorenson is a measure of how closely the regen. layer matches canopy composition. For more details on metric calculations, thresholds and assessment of status, see Miller et al. 2023.
Figure 3. Deer browse impacts by cycle in Gettysburg National Military Park (GETT). Cycle 1: 2007 – 2010; Cycle 2: 2011 – 2014; Cycle 3: 2015 – 2018; Cycle 4: 2019 – 2023.
Figure 4. Loess smoothed changes in stem density for seedlings (A) and saplings (B) by species group and sample year in Gettysburg National Military Park. Specified loess span approximated a linear trend between consecutive sample events per panel.
Figure 5. Loess smoothed changes in tree stem density (A) and basal area (B) by species group and sample year in Gettysburg National Military Park. Specified loess span approximated a linear trend between consecutive sample events per panel.
Figure 6. Loess smoothed changes in invasive plant percent cover by guild and sample year in Gettysburg National Military Park. Specified loess span approximated a linear trend between consecutive sample events per panel.
Table 1. Average plot-level seedling and sapling stem densities (stems per m2) and stocking index (at the 2m radius scale) by cycle. Only native, canopy-forming species are included. Note that Fraxinus spp. (ash species) are no longer considered canopy-forming species. Cycle 1: 2007 – 2010; Cycle 2: 2011 – 2014; Cycle 3: 2015 – 2018; Cycle 4: 2019 – 2023. Plots are sampled in 4-year rotations, with a quarter of the plots sampled each year (i.e. a panel). The stocking index quantifies whether current regeneration densities are sufficient to restock a forest canopy. The index is a weighted sum of seedling and sapling densities where larger seedling size classes get higher weights. Cells highlighted in green are plots that meet the minimum management target of 0.25 seedlings/m2 and 0.14 saplings/m2 or have a stocking index >100. These are the same thresholds used in Figure 2 and are described in Miller et al. 2023.
| Plot | Panel | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 28 | 1 | 4.92 | 6.83 | 1.83 | 1.17 | 0.08 | 0.11 | 0.20 | 0.02 | 204.58 | 380.38 | 246.05 | 18.85 |
| 29 | 1 | 0.00 | 0.00 | 0.08 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 1.01 | 0.00 |
| 30 | 1 | 0.08 | 0.58 | 0.50 | 0.00 | 0.01 | 0.04 | 0.04 | 0.02 | 1.01 | 11.56 | 10.43 | 0.00 |
| 31 | 1 | 2.17 | 2.08 | 2.83 | 2.50 | 0.04 | 0.04 | 0.02 | 0.04 | 36.69 | 40.97 | 132.07 | 276.59 |
| 32 | 1 | 1.17 | 2.08 | 1.67 | 1.25 | 0.01 | 0.01 | 0.00 | 0.02 | 33.55 | 104.80 | 120.39 | 141.50 |
| 33 | 1 | 3.67 | 3.25 | 3.00 | 1.58 | 0.02 | 0.13 | 0.17 | 0.13 | 138.36 | 373.47 | 189.25 | 162.73 |
| 34 | 1 | 2.00 | 2.42 | 1.67 | 1.58 | 0.01 | 0.01 | 0.24 | 0.31 | 117.24 | 294.30 | 289.15 | 319.69 |
| 35 | 1 | 0.50 | 0.17 | 1.42 | 3.92 | 0.05 | 0.05 | 0.05 | 0.05 | 7.29 | 3.14 | 21.99 | 105.81 |
| 87 | 2 | 0.17 | 0.25 | 0.17 | 0.50 | 0.08 | 0.06 | 0.07 | 0.05 | 56.05 | 26.39 | 25.38 | 17.84 |
| 89 | 2 | 1.33 | 0.67 | 0.33 | 0.08 | 0.02 | 0.06 | 0.05 | 0.02 | 127.80 | 131.19 | 46.37 | 28.40 |
| 90 | 2 | 0.00 | 0.00 | 0.08 | 0.08 | 0.01 | 0.02 | 0.04 | 0.00 | 7.41 | 14.83 | 8.42 | 1.01 |
| 91 | 2 | 1.25 | 1.33 | 1.00 | 0.83 | 0.15 | 0.24 | 0.24 | 0.00 | 98.77 | 233.73 | 177.94 | 15.71 |
| 92 | 2 | 0.67 | 0.75 | 1.08 | 0.42 | 0.06 | 0.05 | 0.04 | 0.04 | 10.43 | 13.57 | 19.85 | 25.13 |
| 93 | 2 | 0.50 | 0.25 | 0.42 | 0.25 | 0.13 | 0.12 | 0.11 | 0.08 | 51.52 | 39.96 | 34.68 | 5.28 |
| 96 | 2 | 2.08 | 2.75 | 1.83 | 1.42 | 0.02 | 0.08 | 0.13 | 0.22 | 159.22 | 456.91 | 365.18 | 232.48 |
| 97 | 2 | 0.42 | 0.17 | 0.08 | 0.83 | 0.02 | 0.00 | 0.05 | 0.07 | 14.70 | 54.41 | 31.67 | 104.05 |
| 167 | 3 | 0.67 | 0.42 | 0.25 | 0.00 | 0.04 | 0.02 | 0.02 | 0.01 | 11.56 | 8.42 | 5.28 | 0.00 |
| 168 | 3 | 0.00 | 0.00 | 0.08 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 1.01 | 0.00 |
| 169 | 3 | 0.08 | 0.08 | 0.00 | 0.00 | 0.01 | 0.01 | 0.01 | 0.01 | 1.01 | 1.01 | 0.00 | 0.00 |
| 170 | 3 | 0.17 | 0.42 | 0.42 | 0.42 | 0.00 | 0.01 | 0.02 | 0.04 | 2.14 | 15.83 | 14.70 | 25.26 |
| 171 | 3 | 1.17 | 0.17 | 0.08 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 19.85 | 2.14 | 1.01 | 0.00 |
| 173 | 3 | 0.67 | 1.17 | 0.83 | 0.50 | 0.02 | 0.08 | 0.05 | 0.06 | 78.67 | 106.19 | 60.82 | 22.12 |
| 174 | 3 | 0.42 | 0.42 | 0.50 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 6.28 | 8.42 | 29.28 | 0.00 |
| 175 | 3 | 2.83 | 2.17 | 2.08 | 0.92 | 0.00 | 0.00 | 0.00 | 0.00 | 51.27 | 37.70 | 32.42 | 15.71 |
| 252 | 4 | 0.00 | 0.00 | 0.08 | 0.17 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 1.01 | 2.14 |
| 253 | 4 | 0.58 | 0.67 | 0.50 | 1.00 | 0.18 | 0.17 | 0.05 | 0.14 | 214.51 | 174.42 | 37.82 | 81.30 |
| 254 | 4 | 0.33 | 0.08 | 0.25 | 0.33 | 0.00 | 0.01 | 0.01 | 0.01 | 4.15 | 8.42 | 10.56 | 5.28 |
| 255 | 4 | 0.92 | 1.00 | 1.50 | 1.42 | 0.01 | 0.05 | 0.08 | 0.11 | 38.70 | 68.36 | 176.31 | 121.77 |
| 256 | 4 | 0.17 | 0.08 | 0.33 | 0.25 | 0.00 | 0.00 | 0.00 | 0.00 | 2.14 | 1.01 | 5.28 | 4.15 |
| 257 | 4 | 0.25 | 0.25 | 0.17 | 0.00 | 0.08 | 0.11 | 0.08 | 0.07 | 27.52 | 33.80 | 31.67 | 14.83 |
Table 1 (cont.). Average plot-level seedling and sapling stem densities (stems per m2) and stocking index (at the 2m radius scale) by cycle. Only native, canopy-forming species are included. Note that Fraxinus spp. (ash species) are no longer considered canopy-forming species. Cycle 1: 2007 – 2010; Cycle 2: 2011 – 2014; Cycle 3: 2015 – 2018; Cycle 4: 2019 – 2023. Plots are sampled in 4-year rotations, with a quarter of the plots sampled each year (i.e. a panel). The stocking index quantifies whether current regeneration densities are sufficient to restock a forest canopy. The index is a weighted sum of seedling and sapling densities where larger seedling size classes get higher weights. Cells highlighted in green are plots that meet the minimum management target of 0.25 seedlings/m2 and 0.14 saplings/m2 or have a stocking index >100. These are the same thresholds used in Figure 2 and are described in Miller et al. 2023.
| Plot | Panel | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 258 | 4 | 0.42 | 0.17 | 0.08 | 0.42 | 0.00 | 0.04 | 0.02 | 0.04 | 8.42 | 25.38 | 15.83 | 21.11 |
| 259 | 4 | 0.00 | 0.42 | 0.42 | 0.67 | 0.05 | 0.06 | 0.05 | 0.02 | 0.00 | 6.28 | 9.42 | 15.71 |
| 356 | 2 | - | 2.75 | 2.92 | 2.75 | - | 0.38 | 0.44 | 0.38 | - | 423.36 | 488.71 | 310.89 |
Table 2. Average % cover and number of invasive species detected in each plot by cycle. Cycle 1: 2007 – 2010; Cycle 2: 2011 – 2014; Cycle 3: 2015 – 2018; Cycle 4: 2019 – 2023. Plots are sampled in 4-year rotations, with a quarter of the plots sampled each year (i.e. a panel). Plots with at least 10% average cover or 4 or more invasive species present are in yellow. Average cover and species counts may be increasing over time due to protocol changes, including additions to the indicator species list over time, a plot search for indicator species starting in 2009 and all woody species being sampled in quadrats starting in 2019. More details can be found in the MIDN Summary of Major Protocol Changes
| PlotCode | PanelCode | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 |
|---|---|---|---|---|---|---|---|---|---|
| 28 | 1 | 8.03 | 6.52 | 19.18 | 32.45 | 3 | 4 | 6 | 10 |
| 29 | 1 | 3.69 | 1.99 | 30.17 | 76.27 | 3 | 5 | 6 | 10 |
| 30 | 1 | 67.89 | 34.15 | 54.94 | 54.01 | 5 | 6 | 8 | 8 |
| 31 | 1 | 7.21 | 6.75 | 22.68 | 11.53 | 1 | 2 | 7 | 8 |
| 32 | 1 | 0.29 | 21.58 | 28.00 | 38.15 | 1 | 5 | 8 | 9 |
| 33 | 1 | 5.67 | 11.47 | 9.13 | 4.20 | 2 | 5 | 6 | 8 |
| 34 | 1 | 19.48 | 3.68 | 6.30 | 3.18 | 4 | 5 | 6 | 9 |
| 35 | 1 | 17.21 | 23.36 | 29.52 | 30.01 | 3 | 5 | 5 | 8 |
| 87 | 2 | 4.49 | 15.25 | 4.38 | 17.60 | 3 | 7 | 8 | 8 |
| 89 | 2 | 18.72 | 15.43 | 13.46 | 20.26 | 5 | 7 | 8 | 12 |
| 90 | 2 | 27.57 | 31.19 | 36.16 | 76.49 | 6 | 8 | 8 | 8 |
| 91 | 2 | 2.17 | 2.57 | 6.97 | 20.44 | 4 | 6 | 9 | 8 |
| 92 | 2 | 2.05 | 13.68 | 20.23 | 18.09 | 2 | 6 | 8 | 9 |
| 93 | 2 | 8.75 | 11.79 | 31.42 | 47.96 | 4 | 4 | 8 | 9 |
| 96 | 2 | 14.62 | 3.03 | 3.27 | 4.07 | 5 | 7 | 6 | 9 |
| 97 | 2 | 53.07 | 41.46 | 68.58 | 70.36 | 5 | 6 | 7 | 11 |
| 167 | 3 | 4.55 | 3.24 | 3.73 | 1.51 | 10 | 10 | 9 | 7 |
| 168 | 3 | 61.27 | 70.37 | 75.51 | 69.68 | 6 | 6 | 6 | 7 |
| 169 | 3 | 3.19 | 7.71 | 5.10 | 14.02 | 5 | 6 | 7 | 9 |
| 170 | 3 | 25.20 | 24.57 | 26.16 | 45.57 | 7 | 5 | 7 | 8 |
| 171 | 3 | 26.45 | 24.12 | 25.24 | 24.73 | 7 | 5 | 7 | 8 |
| 173 | 3 | 35.27 | 30.73 | 15.78 | 8.39 | 10 | 10 | 12 | 12 |
| 174 | 3 | 36.17 | 72.79 | 67.49 | 48.10 | 7 | 8 | 6 | 8 |
| 175 | 3 | 3.89 | 0.40 | 1.09 | 3.23 | 5 | 5 | 5 | 8 |
| 252 | 4 | 8.48 | 35.08 | 18.65 | 50.95 | 4 | 6 | 5 | 8 |
| 253 | 4 | 1.02 | 12.22 | 0.42 | 10.89 | 3 | 7 | 6 | 8 |
| 254 | 4 | 2.10 | 3.52 | 6.91 | 2.69 | 3 | 7 | 7 | 9 |
| 255 | 4 | 23.81 | 42.46 | 17.42 | 6.79 | 4 | 5 | 7 | 8 |
| 256 | 4 | 15.46 | 46.50 | 44.23 | 64.18 | 5 | 6 | 5 | 9 |
| 257 | 4 | 0.98 | 16.29 | 9.33 | 3.78 | 4 | 8 | 9 | 7 |
Table 2 (cont.). Average % cover and number of invasive species detected in each plot by cycle. Cycle 1: 2007 – 2010; Cycle 2: 2011 – 2014; Cycle 3: 2015 – 2018; Cycle 4: 2019 – 2023. Plots are sampled in 4-year rotations, with a quarter of the plots sampled each year (i.e. a panel). Plots with at least 10% average cover or 4 or more invasive species present are in yellow. Average cover and species counts may be increasing over time due to protocol changes, including additions to the indicator species list over time, a plot search for indicator species starting in 2009 and all woody species being sampled in quadrats starting in 2019. More details can be found in the MIDN Summary of Major Protocol Changes
| PlotCode | PanelCode | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 |
|---|---|---|---|---|---|---|---|---|---|
| 258 | 4 | 1.02 | 8.79 | 1.09 | 42.54 | 4 | 5 | 6 | 11 |
| 259 | 4 | 0.77 | 5.35 | 7.12 | 3.58 | 4 | 3 | 3 | 6 |
| 356 | 2 | - | 0.00 | 0.16 | 1.63 | - | 3 | 3 | 5 |
Table 3. Number of plots out of 33 where priority invasive species were detected. Cycle 1: 2007 – 2010; Cycle 2: 2011 – 2014; Cycle 3: 2015 – 2018; Cycle 4: 2019 – 2023. Species on the list include all exotic vascular plant species that are capable of dominating Eastern US forest habitats, and does not include all exotic species detected in MIDN forest plots. Average cover and species counts may be increasing over time due to additions to the protocols, including a plot search for additional indicator species starting in 2009 and all woody species being sampled in quadrats starting in 2019. Species have also been added to the indicator list over time. More details can be found in the MIDN Summary of Major Protocol Changes
| Latin Name | Common Name | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 |
|---|---|---|---|---|---|
| Acer platanoides | Norway maple | 3 | 2 | 3 | 8 |
| Ailanthus altissima | Tree of heaven | 3 | 2 | 4 | 10 |
| Alliaria petiolata | garlic mustard | 15 | 15 | 20 | 25 |
| Berberis thunbergii | Japanese barberry | 17 | 24 | 26 | 28 |
| Berberis vulgaris | common barberry | 0 | 1 | 0 | 0 |
| Celastrus orbiculatus | oriental bittersweet | 1 | 2 | 5 | 17 |
| Euonymus | burningbush | 0 | 1 | 1 | 14 |
| Euonymus fortunei | climbing euonymus | 0 | 1 | 0 | 1 |
| Ligustrum | privet | 3 | 17 | 15 | 18 |
| Lonicera - Exotic | honeysuckle - exotic | 6 | 10 | 17 | 15 |
| Lonicera japonica | Japanese honeysuckle | 29 | 31 | 31 | 32 |
| Microstegium vimineum | Japanese stiltgrass | 25 | 26 | 32 | 31 |
| Oplismenus hirtellus ssp. undulatifolius | wavyleaf basketgrass | 0 | 0 | 0 | 2 |
| Persicaria longiseta | Oriental lady's thumb | 7 | 12 | 21 | 18 |
| Persicaria perfoliata | Asiatic tearthumb | 0 | 1 | 2 | 7 |
| Rosa multiflora | multiflora rose | 26 | 32 | 31 | 33 |
| Rubus phoenicolasius | wine raspberry | 9 | 16 | 14 | 19 |
Table 4. Invasive plant and pest/pathogen early detections in Gettysburg National Military Park observed in the most recent census of each plot. Coordinates are in UTM NAD83 Zone 18N.
| Plot | Year | X | Y | Latin Name | Common Name | Type |
|---|---|---|---|---|---|---|
| GETT-256 | 2023 | 307348 | 4405807 | Oplismenus hirtellus ssp. undulatifolius | wavyleaf basketgrass | graminoid |
| GETT-097 | 2022 | 307117 | 4411757 | Oplismenus hirtellus ssp. undulatifolius | wavyleaf basketgrass | graminoid |
| GETT-175 | 2022 | 308602 | 4406809 | Ailanthus altissima | Tree of heaven | tree |
| GETT-253 | 2023 | 308096 | 4406818 | Ailanthus altissima | Tree of heaven | tree |
| GETT-169 | 2022 | 308610 | 4407043 | Ailanthus altissima | Tree of heaven | tree |
| GETT-171 | 2022 | 309851 | 4408809 | Ailanthus altissima | Tree of heaven | tree |
| GETT-031 | 2019 | 306841 | 4407290 | Ailanthus altissima | Tree of heaven | tree |
| GETT-089 | 2022 | 310343 | 4410057 | Ailanthus altissima | Tree of heaven | tree |
| GETT-032 | 2019 | 307589 | 4406049 | Ailanthus altissima | Tree of heaven | tree |
| GETT-091 | 2022 | 308602 | 4407302 | Ailanthus altissima | Tree of heaven | tree |
| GETT-258 | 2023 | 310104 | 4409815 | Ailanthus altissima | Tree of heaven | tree |
| GETT-096 | 2022 | 307607 | 4407317 | Ailanthus altissima | Tree of heaven | tree |
| GETT-033 | 2019 | 310357 | 4409298 | Albizia julibrissin | silktree | tree |
| GETT-028 | 2019 | 310101 | 4409555 | Albizia julibrissin | silktree | tree |
| GETT-257 | 2023 | 306605 | 4412050 | Albizia julibrissin | silktree | tree |
| GETT-255 | 2023 | 308845 | 4408550 | Albizia julibrissin | silktree | tree |
| GETT-033 | 2019 | 310357 | 4409298 | Agrilus planipennis | emerald ash borer | pest |
| GETT-093 | 2022 | 307603 | 4413545 | Agrilus planipennis | emerald ash borer | pest |
| GETT-087 | 2022 | 309127 | 4408804 | Agrilus planipennis | emerald ash borer | pest |